Materials handling vehicles are known in the prior art comprising a power unit and a mast assembly. The mast assembly may comprise first, second and third mast weldments, wherein the second mast weldment is capable of moving relative to the first mast weldment and the third mast weldment is capable of moving relative to the second mast weldment. First and second lift ram/cylinder assemblies are coupled between the first and second mast weldments for effecting movement of the second and third mast weldments relative to the first mast weldment. Coupled to the third mast weldment is a movable fork carriage assembly. A further ram/cylinder unit is provided for effecting movement of the fork carriage assembly relative to the third mast weldment.
The power unit includes manifold apparatus mounted on a front portion of a frame of the power unit. The manifold apparatus includes valve structure for controlling fluid flow to the first and second ram/cylinder assemblies coupled between the first and second weldments and the ram/cylinder assembly coupled between the third weldment and the fork carriage assembly. The manifold apparatus further includes valve structure for controlling fluid flow to ram/cylinder assemblies for tilting the mast assembly relative to the power unit and at least one auxiliary device such as a fork side shift mechanism, a carton clamp, a fork reach mechanism, a paper roll clamp or a slip sheet device.
The truck may further include a manifold on the fork carriage assembly including one or two mechanical cross-over relief valves for diverting hydraulic fluid from a corresponding auxiliary device to a fluid storage reservoir if the fluid pressure provided to the corresponding auxiliary device exceeds a threshold value. One or more mechanical valves for limiting the maximum rate of descent of the fork carriage assembly and the second and third mast weldments may also be provided in the manifold provided on the fork carriage assembly.
It is also known in another prior art materials handling vehicle to provide a manifold apparatus mounted on a fork carriage assembly having first and second auxiliary select valves, which valves are electronically controlled ON/OFF valves for selecting operation of a desired auxiliary unit. It is noted that fluid flow to the selected auxiliary device is controlled via a valve mounted in a manifold apparatus on a power unit.
It is further known to provide a manifold apparatus on a carriage of a reach truck. The manifold apparatus includes structure for selecting functions such as tilt, side shift and reach. Fluid flow rate is not controlled by valve structure contained in the manifold apparatus on the carriage. Instead valves are provided in a manifold mounted on a power unit for controlling fluid flow for those functions.
It is still further known in a prior art materials handling vehicle to provide a manifold apparatus on a first weldment of a mast assembly, wherein the first weldment does not move vertically. The manifold apparatus comprises one or more mechanical valves for limiting the maximum rate of descent of a fork carriage assembly and second and third mast weldments.
It would be desirable to mount a manifold apparatus on a mast assembly, which manifold apparatus performs functions typically performed by manifolds mounted on a power unit so as to reduce the volume or size of the power unit.